U0027

U0027-CAN B BUS (-) SHORTED TO BUS (+)





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams.

- When Monitored:
Continuously

- Set Condition:
The Front Control Module (FCM) detects the (D55) CAN B Bus (+) circuit is shorted to the (D54) CAN B Bus (-) circuit.





1. TEST FOR INTERMITTENT CONDITION
1. Turn the ignition on.
2. Using the scan tool, record and erase FCM Diagnostic Trouble Codes (DTCs).
3. Cycle the ignition from on to off three times.
4. Turn the ignition on.
5. Using the scan tool, read active FCM DTCs.

Does the scan tool display this DTC as active?

Yes

- Go To 2

No

- The conditions that caused this code to set are not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.

2. CHECK THE (D55) CAN B BUS (+) CIRCUIT FOR A SHORT TO THE (D54) CAN B BUS (-) CIRCUIT




1. Turn the ignition off.
2. Disconnect the Front Control Module C1 harness connector.
3. Measure the resistance between the (D55) CAN B Bus (+) circuit and (D54) CAN B Bus (-) circuit.

Is resistance below 1000.0 Ohms?

Yes

- Go To 3

No

- Inspect the wiring and connectors for damage or shorted circuits. If ok, replace the Front Control Module.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

3. (D55) CAN B BUS (+) CIRCUIT SHORTED TO THE (D54) CAN B BUS (-) CIRCUIT




1. Measure the resistance between the (D55) CAN B Bus (+) circuit and (D54) CAN B Bus (-) circuit.
2. While monitoring the ohmmeter, disconnect each CAN B Bus module one at a time.

NOTE: This is to determine if the short is internal within a module or if the circuits are shorted together.

NOTE: Disconnecting an in-line connector can eliminate a module or group of modules from the list of possible causes for this fault. Refer to the wiring diagrams to assist in diagnosis.

Is resistance below 1000.0 Ohms with all the CAN B Bus modules disconnected?

Yes

- Repair the (D55) CAN B Bus (+) circuit for a short to the (D54) CAN B Bus (-) circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.

No

- Replace the module that when disconnected, the short to ground was eliminated,.
- Perform the BODY VERIFICATION TEST. Body Verification Test.